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Polar bears head north as Arctic warms

As sea ice disappears, polar bears are on the move. Now, a new study shows where many of the bears have gone over the past 2 decades: north toward the Canadian archipelago, one of the last Arctic regions to be affected by climate change. Starting in the 1980s, researchers collected tissue or hair samples from nearly 3000 polar bears captured by scientists or killed by hunters throughout the Arctic. DNA analyses showed that bears from different regions are genetically distinct from one another, allowing researchers to approximate the bears’ movements by tracking changes in the population’s genetic makeup over time. Over the past 20 years, polar bears from southern Canada and the eastern polar basin have migrated north, where year-round sea ice persists, the authors report this month in PLOS ONE. The northern regions of the Canadian archipelago are expected to retain sea ice longer than other Arctic areas, researchers say, and will likely continue to provide an important refuge for the migrating animals—at least for now.